geometry help with probability

Question

The illustration represents the positions of two planes on a radar screen at an airport control tower. The control tower is located at the origin. The radii of the circles are in miles. 

Due to a problem on the ground, the pilots have been told to continue circling the airport and to maintain the same airspeed. The planes are located at the same altitude. Determine the equation of the circle on which the two planes are flying.

answer: (x -  )² + (y -  )² =  _²

there is a picture but it wont submit

Answer 1

The generic equation for a circle is (x - h)² + (y - k)² = r² where the center of the circle is at the point (h, k) and the radius is r. In this case, since the control tower is located at the origin, we can just use x2 + y2 = r2. So look at the picture and find the distance away from the control tower to find r. Depending on the picture, you may need to calculate r using the Pythagorean Theorem or something. For instance if it shows something like this